Sulfate attack of Algerian cement-based material with crushed limestone filler cured at different temperatures

Authors: SENHADJI YASSINE, MOULI MOHAMED, KHELAFI HAMID, BENOSMAN AHMED SOFIANE

Abstract: The cement production industry is one of the main consumers of energy and raw materials. Over the last years, a great effort has been made in order to substitute clinker for less energy demanding materials. In many countries, it is popular to use limestone as admixture material to improve the consistency of concrete. Nevertheless, the construction industry needs durable materials with improved properties. Following this objective, this work is a part of an ongoing project developed in the materials laboratory of LABMAT/ENSET, Oran, Algeria. This paper presents data on engineering properties such as compressive strength and visual change of mortar specimens incorporating limestone filler, subjected to severe sulfate attack and cured at: (i) 5 °C and (ii) 23 °C. Specimens with 4 replacement levels of limestone filler (0%, 10%, 20%, and 30% of cement by mass) were immersed in magnesium sulfate solutions with 5% of concentration for periods of up to 360 days. In order to identify the products formed by sulfate attack, microstructural analyses, such as XRD and SEM, were also performed on paste and mortar samples with similar replacement levels of limestone filler. The test results demonstrated that mortar and paste samples incorporating higher replacement levels of limestone filler were more susceptible to sulfate attack at low temperatures. On top of that, the deterioration was strongly associated with thaumasite, gypsum, and brucite formation in the magnesium sulfate solution.

Keywords: Crushed limestone fillers, Microstructure, Reduction in compressive strength (RCS), X-ray, Thaumasite, MgSO_4 solution

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